Policy and Charging Control Method, Network Entities, Communication System and Computer Program Therefor

1. A policy and charging control method carried out in a communication network, the communication network comprising a first network entity, PCRF, including a policy and charging rules function and a second network entity, PCEF, including a policy and charging enforcement function to enforce policy and charging rules in at least two groups of cells, each group of cells including at least one cell, the method comprising: configuring, on the second network entity, for a first group of the at least two groups of cells, an event subscription dependent on a location of the user equipment, the event subscription being specific to the first group of cells; at the second network entity, detecting an event associated with the configured event subscription and sending a notification of the detected event to the first network entity; at the first network entity, after receipt of the notification, determining whether to perform one among installing, modifying and removing a policy and charging control rule in dependence of the detected event, wherein the event subscription further depends on at least a user profile associated to a user of the user equipment, wherein the user profile indicates areas defined for the user of the user equipment, and wherein at least one area in the user profile corresponds to the first group of cells.

2. The policy and charging control method according to claim 1 , wherein the configuring is performed beforehand and later associated to the user when the user enters the first group of cells.

3. The policy and charging control method according to claim 1 , wherein the event subscription is configured based on configuration information received at the second network entity from at least one among the first network entity and a further network entity.

4. The method according to claim 1 , wherein the event subscription comprises a subscription to at least an event, the event being dependent on the location of the user equipment.

5. The method according to claim 1 , wherein the detected event comprises at least one among the user equipment entering one of the group of cells and leaving one of the group of cells.

6. The method according to claim 1 , further comprising, when it is determined at least one among installing, modifying and removing a policy and charging control rule in dependence of the detected event, performing a corresponding step comprising, respectively, installing a new policy and charging control rule, modifying an existing policy and charging control rule, and removing an existing policy and charging control rule.

7. The method according to claim 1 , further comprising: establishing or modifying a communication session between the user equipment and the second entity; and requesting policy and charging rules for the communication session from the first network entity, wherein the step of configuring the event subscription is performed in response to the step of requesting the policy and charging rules.

8. A network entity configured to perform a policy and charging rules function in a communications network, the network entity comprising: a controller adapted to determine event subscription information based on a location of a user equipment, the event subscription information being specific to a first group of at least two groups of cells, each group of cells including at least one cell; a transmitter adapted to send the event subscription information to a second network entity; and a receiver adapted to receive from the second network entity a notification corresponding to an event detected according to the event subscription information, wherein the controller is further adapted to further determine, upon receipt of the notification, whether to instruct the second network entity to perform one among installing, modifying or removing a policy and charging control rule in dependence of the detected event, wherein the controller is further adapted to further determine the event subscription information based on at least a user profile associated to a user of the user equipment, wherein the user profile indicates areas defined for the user of the user equipment, and wherein at least one area in the user profile corresponds to the first group of cells.

9. The network entity according to claim 8 , further adapted to determine the event subscription information beforehand and to later associate the event subscription information to the user when the user enters the first group of cells.

10. The network entity according to claim 8 , wherein the controller is further adapted to maintain a relationship among the event subscription information and a communication session between the user equipment and the second network entity.

11. The network entity according to claim 8 , wherein the controller is further adapted, when it is determined to install, modify or remove a policy and charging control rule in dependence of the detected event, to instruct the second network entity to perform a corresponding operation of, respectively, installing a new policy and charging control rule, modifying an existing policy and charging control rule, or removing an existing policy and charging control rule.

12. A network entity configured to perform a policy and charging enforcement function to enforce policy and charging rules in at least two groups of cells in a communications network, each group of cells including at least one cell, the network entity comprising: a controller adapted to configure, for a first group of the at least two groups of cells, at least an event subscription dependent on a location of a user equipment, the event subscription being specific to the first group of cells; a detector adapted to detect an event associated with the configured event subscription; and a receiver adapted to receive instructions from a first network entity to install, modify or remove policy and charging rules depending on the detected events, wherein the event subscription further depends on at least a user profile associated to a user of the user equipment, wherein the user profile indicates areas defined for the user of the user equipment, and wherein at least one area in the user profile corresponds to the first group of cells.

13. The network entity according to claim 12 , wherein the event subscription is configured beforehand and later associated to the user when the user enters the first group of cells.

14. The network entity according to claim 12 , wherein the controller is further adapted to receive event subscription information from one among a first network entity and a further network entity.

15. The network entity according to claim 12 , wherein the controller is further adapted to maintain a relationship among the event subscription and a communication session between the user equipment and the second network entity.

16. The network entity according to claim 12 , wherein the controller is adapted to exchange information corresponding to the event subscription with a further network entity configured to communicate with the user equipment.

17. The network entity according to claim 12 , further comprising a transmitter adapted to send a notification of the detected event to the first entity.

18. A communication system arranged to perform policy and charging in a communications network, the communication system comprising: a first network entity comprising: a first controller adapted to determine event subscription information based on a location of a user equipment, the event subscription information being specific to a first group of at least two groups of cells, each group of cells including at least one cell; and a second network entity comprising: a second controller adapted to configure, for the first group of cells and based on the event subscription information, an event subscription dependent on the location of the user equipment, the event subscription being specific to the first group of cells; and a detector adapted to detect an event associated with the configured event subscription and adapted to send to the first network entity a notification corresponding to an event detected according to the event subscription, wherein the first controller is further adapted to determine, upon receipt of the notification, whether to instruct the second network entity to perform one among installing, modifying or removing a policy and charging control rule in dependence of the detected event, wherein the event subscription further depends on at least a user profile associated to a user of the user equipment, wherein the user profile indicates areas defined for the user of the user equipment, and wherein at least one area in the user profile corresponds to the first group of cells.

19. The communication system according to claim 18 , further adapted to determine the event subscription information beforehand and to later associate the event subscription information to the user when the user enters said first group of cells.

20. A computer program for performing a policy and charging rules function in accordance with a location of a user equipment in a communications network, the computer program comprising instructions configured, when executed on a programmable system, to cause the programmable system to carry out the method steps according to claim 1 .